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Finding the Fourth Proportional to 680.18, 1,018.65 and 390.74

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Solution

The fourth proportional to 680.18, 1,018.65 and 390.74 is: 585.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.18 : 1,018.65 = 390.74 : x
  2. Step 2: Convert to fraction form
    680.18/1,018.65 = 390.74/x
  3. Step 3: Cross multiply
    680.18x = 1,018.65 × 390.74
  4. Step 4: Simplify right side
    680.18x = 398,027.30
  5. Step 5: Solve for x
    x = 398,027.30/680.18
  6. Step 6: Final answer
    x = 585.18

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.